|Origin:||observer, from Latin observare 'to guard, watch', from servare 'to keep'|
1 [transitive not in progressive] formal
to see and notice something:
Scientists have observed a drop in ozone levels over the Antarctic.
It was observed that 40 percent of patients had high blood pressure.
observe somebody doing something
Officers observed him driving at 90 miles per hour.
Predators have been observed to avoid attacking brightly coloured species.
2 [intransitive and transitive]
to watch something or someone carefully:
The police have been observing his movements.
One student performs the experiment, while his partner observes.
Observe how the people in the group interact.
3 [transitive] formal
to say or write what you have noticed about a situation:
'Sid looks ill,' Doherty observed.
Keynes observed that humans fall into two classes.
to do what you are supposed to do according to a law or agreement [= obey]:
So far the ceasefire has been observed by both sides.
to do things and obey laws that are part of a religion or custom